For the intellect is uncontrollable, not because it is by nature ever-active, but because through our continual remissness it has been given over to distraction and has become used to that.
When we violated the commandments of Him who in baptism regenerates us we separated ourselves from God and lost our conscious awareness of Him and our union with Him.
Sundered from that union and estranged from God, the intellect is led captive everywhere; and it cannot regain its stability unless it submits to God and is stilled by Him, joyfully uniting with Him through unceasing and diligent prayer and through noetically confessing all our lapses to Him each day.
God immediately forgives everything to those who ask forgiveness in a spirit of humility and contrition and who ceaselessly invoke His holy name. As the Psalmist says, “Confess to the Lord and call upon His holy name” (Psalms 105:1).
Holding the breath also helps to stabilize the intellect, but only temporarily, for after a little it lapses into distraction again. But when prayer is activated, then it really does keep the intellect in its presence, and it gladdens it and frees it from captivity.
But it may sometimes happen that the intellect, rooted in the heart, is praying, yet the mind wanders and gives its attention to other things; for the mind is brought under control only in those who have been made perfect by the Holy Spirit and who have attained a state of total concentration upon Christ Jesus.
In the case of a beginner in the art of spiritual warfare, God alone can expel thoughts, for it is only those strong in such warfare who are in a position to wrestle with them and banish them. Yet even they do not achieve this by themselves, but they fight against them with God’s assistance, clothed in the armor of His grace.
So when thoughts invade you, in place of weapons call on the Lord Jesus frequently and persistently and then they will retreat; for they cannot bear the warmth produced in the heart by prayer and they flee as if scorched by fire.
St. John Climacus tells us, “Lash your enemies with the name of Jesus,” because God is a fire that cauterizes wickedness (Deuteronomy 4:24 and Hebrews 12:29). The Lord is prompt to help, and will speedily come to the defense of those who wholeheartedly call on Him day and night (Luke 18:7).
Gregory of Sinai (1260s–1346): On Prayer, Text from G.E.H. Palmer, Philip Sherrard, and Kallistos Ware (trans. and eds.) The Philokalia: The Complete Text, vol. 4 (Faber & Faber, London & Boston: 1979ff), pp. 276-278.
**The translators of the Philokalia say the following about the word “intellect” as used in this passage from Gregory and by other Greek authors: INTELLECT (nous): the highest faculty in man, through which – provided it is purified – he knows God or the inner essences or principles of created things by means of direct apprehension or spiritual perception. Unlike the dianoia or reason, from which it must be carefully distinguished, the intellect does not function by formulating abstract concepts and then arguing on this basis to a conclusion reached through deductive reasoning, but it understands divine truth by means of immediate experience, intuition or ‘simple cognition’ (the term used by St Isaac the Syrian). The intellect dwells in the ‘depths of the soul’; it constitutes the innermost aspect of the heart (St Diadochos). The intellect is the organ of contemplation, the ‘eye of the heart’ (Macarian Homilies).